A Simple Blood-Based Biomarker (SIRI) Predicts Outcomes in Metastatic Pancreatic Cancer: Pancreatology | August 2026
Introduction:
Systemic inflammation plays a major role in pancreatic ductal adenocarcinoma (PDAC), contributing to tumor progression, cachexia, and treatment resistance. The Systemic Inflammation Response Index (SIRI) combines neutrophil, monocyte, and lymphocyte counts into a readily available blood-based biomarker. This multicenter study evaluated its prognostic value in metastatic PDAC receiving first-line chemotherapy.
Why was this study needed?
Outcomes with metastatic PDAC remain highly heterogeneous despite modern chemotherapy.
Systemic inflammation influences treatment tolerance and tumor progression.
Complex cytokine profiling is impractical for routine clinical care.
A simple biomarker derived from standard blood counts could improve prognostic stratification.
Results:
Among 672 patients across 30 centers, low SIRI (≤2.3) was associated with substantially longer survival: 14.0 vs 9.2 months.
High SIRI predicted shorter progression-free survival and lower chemotherapy response rates.
SIRI remained an independent predictor of outcome after adjustment for other clinical factors.
Higher SIRI was also associated with greater liver tumor burden and cachexia, identifying a more aggressive inflammatory phenotype.
Clinical Impact:
SIRI provides an inexpensive and readily available method of identifying metastatic PDAC patients with poor prognosis and reduced likelihood of chemotherapy response. Because it relies only on routine blood counts, it could complement performance status, disease burden, nutritional assessment, and other biomarkers when discussing prognosis and treatment intensity. Prospective validation is needed before using SIRI to select specific chemotherapy regimens.
Bottom Line:
High SIRI identifies metastatic pancreatic cancer with greater systemic inflammation, poorer chemotherapy response, and shorter survival. This simple blood-based index could become a practical tool for prognostic stratification and personalized treatment planning in advanced PDAC.
